The Study Of Prosulfuron Hydrolysis And Photolysis Characteristics

Prosulfuron belongs to sulfonylurea herbicides which was developed byNovartis, Switzerland. It was largely used for the control of gramineae grasses andbroad-leafed weed species in the corn fields. This pesticide has good effects of weedcontrolling with low dosage, safe and better prospection compared with other kinds ofherbicides. Meanwhile, it has not been studied about the migration and transformationin the environment as a new pesticide. So the research of the degradation process ofprosulfuron in the environment is essential. In order to evaluate its influences to theenvironment precisely, we investigate the variation of photolysis and hydrolysis ofprosulfuron by using the liquid chromatography.Six factors were studied such as different pH as buffer solutions, initialconcentrations, tempretures, metal ions, humic acid to seek the regulation ofprosulfuron’s hydrolysis. In acidic,neutral,alkaline solutions, The results showed thatthe hydrolysis rate was pH＞pH5＞pH7, the reason is that the reaction of nucleophilicsubstitution between hydroxy and methoxy in alkaline solutions with the fracture ofurea bridge. The hydrolysis rate of prosulfuron was negatively correlated with theinitial concentrations. The larger the initial concentration was the rate of hydrolysiswas decreased. The result of the hydrolysis rate in different kinds of water was thatYitong river> rice field water>lake water>distilled water. Substances in natural wateraccelerated the hydrolysis reaction rate of prosulfuron. Adding Cu2+can significantlychange the hydrolysis rate, the result was better than adding Zn2+;there are amount ofhumic acid in soil and water and it has great effects on the hydrolysis rate. Theconcentration of humic acid was positively correlated with it.The research of the properties of prosulfuron conducted from different pH, water,organic solvents, UV absorbers and lights. The photolysis rate was rapid with neutraland alkaline buffer solutions when photolysis under mercury lamp with300w, whilein acidic buffer solution the reaction was relatively slow. The half-lifes were0.1d,0.2d,33.6d in pH9, pH7, pH5buffer solutions. The results showed that photolysis indifferent water, was Yitong river>distilled water>lake water>rice field water,photolysis’s half-lifes were14.2h,54.6h,69.3h,72.7h. Acetonitrile was the fastestand the slowest was hexane when photolysis in various organic solvents, thephotolysis rate order:Acetonitrile>methanol> Dichloromethane> Chloroform> hexane. UV absorbers of UV-P and UP-531had an obviously inhibiting effect.Finally we can concluded the degradation rate of prosulfuron was that500w>300w>xenon lam.